As a multi-functional histone demethylase, PHF8 has been shown to be overexpressed in various cancers including prostate cancer.21, 24, 25, 26, 35 Furthermore, PHF8 has been identified through a systematic screening of epigenetic enzymes as a novel demethylase with an impact on cell proliferation, migration and invasion of prostate cancer cells.24 In this study, we provide evidence that PHF8 interacts with and functions as a coactivator for the AR and that PHF8 enhances AR transcriptional activation in a demethylase activity-dependent manner (Figures 1 and 2). This evidence concerns the gene AR and Familial prostate cancer.